This invention relates generally to electric motors and more particularly, to an endshield assembly for an electric motor.
Known electronically commutated motors have a multi-stage winding assembly and a magnetic assembly associated for relative rotation. The winding stages of the multi-stage winding assembly have a preset energization sequence that includes at least one unenergized winding stage in which an induced back EMF appears. When integrated over time to a predetermined value, the induced back EMF indicates the instant at which the relative angular position between the multi-stage winding assembly and the magnetic assembly is suitable for the sequential commutation of the next winding stage.
The electronic circuitry for an electronically commutated motor generally includes a power circuit, a regulating circuit, and a control circuit. The power circuit has solid state switching devices for commutating the power supplied to the electronically commutated motor to effect its energization. The regulating circuit has various solid state components for maintaining the power supplied to the electronically commutated motor generally constant. The control circuit has various solid state components for controlling the conductivity of the switching devices.
Some of the solid state components for an electronically commutated motor, e.g., transistors, need to be relatively large to accommodate the currents that must pass trough them. Large transistors can produce a sizable amount of heat that should be dissipated from the transistors in order to keep them functioning properly. It is well known in the art that to promote heat dissipation, the electronic circuitry for an electronically commutated motor can be positioned adjacent an outer surface of an endshield of the motor. However, this increases costs since another compartment is needed to protect the electronic circuitry.
Accordingly, it would be desirable to provide a mounting arrangement for the electronic components of an electronically commutated motor that provides good heat dissipation without significantly increasing the cost of the motor. Additionally, it would be desirable to eliminate the additional compartment needed to protect the electronic circuitry.